Beyond the Window: Patient Characteristics and Geographic Locations Associated with Late Prenatal Care in Women Eligible for 17-P Preterm Birth Prevention

Introduction: To reduce the risk of recurrence, women with a history of spontaneous preterm birth (PTB) are recommended to receive 17-hydroxyprogesterone caproate (17-P) injections starting by the 20th week of pregnancy. In women eligible for 17-P, we aimed to identify patient factors and geospatial locations associated with increased risk of presentation beyond 20 weeks gestation. Methods: We conducted a secondary analysis of a retrospective cohort study including all women meeting criteria for 17-P within a single academic medical center over a 2-year period. We compared early (< 20 6/7 weeks) with late (> 21 weeks) presenters via demographics, social history, and index pregnancy outcomes using standard and Bayesian statistical models. Geospatial mapping was performed to determine residential areas with high risk for late presentation. Results: Geocoded address data was available for 351 women in whom the mean gestational age at first visit was 14.9 weeks, and 63 of whom were late presenters (17.9%). Younger maternal age, current smoking, and lack of health insurance were predictors of late presentation with greater than 95% probability. Hispanic ethnicity and black race were associated with higher odds of late presentation with 87 and 69% probability, respectively. The area with the latest gestational age at presentation was located within central Durham City and to the northeast. Discussion: Our study identified patient-level risk factors and geographic locations associated with presentation beyond the recommend window for 17-P initiation. These findings suggest an urgent need for intervention to improve early prenatal care initiation and a target location where such interventions will be most impactful.